Crop strippers and stripper toothing

Abstract

A crop stripper has a rotor provided with metal stripping teeth. The teeth each have an outwardly tapering outer portion extending from a radially inner root portion of arcuate form which provides a root opening between adjacent teeth wider than the spacing between the teeth at the junctions of the inner and outer portions. Along each outer portion the edges of the teeth have flanging which terminates short of the inner portions. The flanging extends over not substantially more than 70%, preferably not more than 60%, of the length of the teeth. The stripping teeth are supported by shorter and thicker backing teeth placed behind the stripping teeth in the direction of rotation of the rotor.

What is claimed is:  
     
       1. A crop stripper rotor comprising at least one series of stripping teeth disposed side by side at a spacing from each other, said teeth extending radially outwardly from the axis of rotation of the rotor, each tooth having a profile with a root portion in a radially inner region relative to the rotor axis and a radially outer tapering portion relative to the rotor axis tapering towards a radially outer tip of the tooth, a neck portion between said inner root portion and said outer tapering portion, the spacing between each adjacent pair of teeth being increased in said root portions to form a root opening between said pair of teeth having a maximum width greater than the spacing between the teeth at said neck portion, flanging along said tapering outer portions of the teeth, said flanging extending over between 10% and 90% of the radial length of said outer tapering portions from said radially outer tips. 
     
     
       2. A rotor according to claim  1  wherein said flanging extends over not substantially more than 60% of a radial length of the tooth profile measured in a radial direction from the radially inner extremity of the root opening. 
     
     
       3. A stripper rotor according to claim  1  wherein said series of teeth have a pitch defined as the distance between the centers of successive root openings, and the minimum spacing between the flanging of adjacent teeth is not less than 20% of the pitch of the teeth. 
     
     
       4. A stripper rotor according to claim  3  wherein the minimum spacing between the flanging of adjacent teeth is not substantially less than 25% of said pitch. 
     
     
       5. A stripper rotor according to claim  1  wherein a gap between adjacent teeth across radially inner ends of the flanging is approximately equal to the width of the root openings at said neck portions. 
     
     
       6. A stripper rotor according to claim  1  wherein said flanging on the tapering outer portions of the teeth extends between 30 to 80% of said radial length. 
     
     
       7. A stripper rotor according to claim  1  wherein the flanging extends around the outer tip of the outwardly tapering portion of each tooth, the tip flanging having an increased depth relative to the flanging radially inwards of said outer tip. 
     
     
       8. A stripper rotor according to claim  7  wherein said tip flanging is at least 25% deeper than the flanging radially inwards of said outer tip. 
     
     
       9. A stripper rotor according to claim  7  wherein said tip flanging has a depth of 20% to 200% more than the flanging radially inwards from said tip. 
     
     
       10. A stripper rotor according to claim  9  wherein said tip flanging has a depth between 50% and 100% more than the flanging radially inwards from said tip. 
     
     
       11. A stripper rotor according to claim  1  wherein the depth of the flanging on each said tooth reduces from a radially inner end of the flanging over at least a major portion of the radial extent thereof. 
     
     
       12. A stripper rotor according to claim  11  wherein the flanging depth varies in the range of 1 mm to 10 mm. 
     
     
       13. A stripper rotor according to claim  12  wherein the flanging depth varies in the range of 3 mm to 8 mm. 
     
     
       14. A stripper rotor according to claim  6  wherein said flanging on the tapering outer portions of the teeth extends between 40% and 65% of said outer portion length. 
     
     
       15. A stripper rotor according to claim  1  wherein the flanging of each tooth is inclined from a main plane of the tooth from which it extends at an angle of between 0° and 60° as measured between a normal to said main plane and a tangent to an outer edge region of the flanging. 
     
     
       16. A stripper rotor according to claim  1  wherein the flanging has a continuously curved section transverse to each tooth over at least a greater part of its depth. 
     
     
       17. A stripper rotor according to claim  1  wherein backing supports are provided behind said series of teeth, said supports comprising further teeth extending radially outwardly beyond the root portions of said series of teeth and at least part way along the tapering outer portions of said series of teeth. 
     
     
       18. A stripper rotor according to claim  17  wherein said further teeth are formed from plastic and are thicker than said series of teeth. 
     
     
       19. A stripper rotor according to claim  17  wherein said further teeth extend into the flanged outer portions of said series of teeth. 
     
     
       20. A stripper rotor according to claim  19  wherein said further teeth extend over the inner 20-50% of the radial length of the flanging of said series of teeth. 
     
     
       21. A stripper rotor according to claim  1  wherein the stripping teeth are selectably mountable in place on the rotor with the flanging extending either forwards or rearwards with respect to a chosen direction of rotation of the rotor. 
     
     
       22. A crop stripper having a rotor comprising a central core and a plurality of series of stripping teeth projecting radially outwardly from an outer periphery of the core at equal angular intervals, in each said series the teeth being disposed side by side at a spacing from each other, each tooth having a profile with a radially inner root portion adjacent to said core periphery and a radially outer portion tapering towards a radially outer tip of the tooth, a neck portion between said inner root portion and said outer tapering portion, the spacing between each adjacent pair of teeth being increased in said root portions to form a root opening between said pair of teeth having a maximum width greater than the spacing between the teeth at said neck portion, said root opening having a radially inner extremity, flanging along said tapering outer portions of the teeth, said flanging extending from said tip over not substantially more than 60% of a radial length of the tooth profile measured from the radially inner extremity of the root opening and terminating outwardly from said neck portion. 
     
     
       23. A comb plate comprising a series of stripping teeth for a stripper rotor, the teeth being disposed side by side at a spacing from each other, each tooth extending radially outwardly relative to the axis of the rotor and having a profile with a radially inner root portion and a radially outer portion tapering towards an outer tip of the tooth, a neck portion between said inner root portion and said outer tapering portion, the spacing between each adjacent pair of teeth being increased in said root portions to form a root opening between said pair of teeth having a maximum width greater than the spacing between the teeth at said neck portion, said root opening having an inner extremity, flanging along said tapering outer portions of the teeth, said flanging extending from said tip over not substantially more than 60% of a length of the tooth profile between said outer tip and the inner extremity of the root opening and terminating outwardly from said neck portion. 
     
     
       24. A comb plate for a stripper rotor comprising a series of metal stripping teeth disposed side by side at a spacing from each other, each tooth extending radially outwardly relative to the axis of the rotor and having a profile with a radially inner root portion and a radially outer portion tapering towards a radially outer tip of the tooth, a neck portion between said inner root portion and said outer tapering portion, the spacing between each adjacent pair of teeth being increased in said root portions to form a root opening between said pair of teeth having a maximum width greater than the spacing between the teeth at said neck portion, flanging on edges of said teeth spaced from the root portions, said flanging extending from the outer tips of the teeth over between 10% and 90% of the radial length of said tapering portions. 
     
     
       25. A comb plate according to claim  24  wherein said flanging extends from the outer tips over not substantially more than 60% of the length of the tooth profile between said outer tip and the radially inner extremity of the root opening.